With the advent of steam flooding projects, i.e. in oil recovery from oil fields that need stimulation to produce the oil, there is a need for a simple method to determine the quality of steam at the well head of an injection well. Such a measurement would be particularly useful to determine the heat input to the underground reservoir. The measurement is important because steam quality directly affects production operations, earnings and future investment requirements. In the past, the desired information was not obtainable after a steam supply had been split by use of a manifold which separated the liquid and vapor components of the steam. However, by use of a method according to this invention, the quality measurements may be directly made individually for steam lines supplying each injection well.